[Faisal_khan]

So you mean you want to set the players position to the lowest Z co-ordinate i.e. the ground? Well there is a plugin as well as an include for that the plugin name is MapAndreas the include name is also somewhat same try searching the forums for it. Its on you what you wanna choose plugin or include. I will prefer include since it consumes less memory and is of less KB's while the plugin is 22 MB and it consumes some near 70 MB of your memory.

Wish you luck!